The present invention relates to a serial printer and, more particularly, to a serial printer of the type in which a carriage carrying a type cylinder is moved along the line to be printed and, at each position of the carriage, one of the type elements on the periphery of the type cylinder is selectively pressed against a record paper to print the character corresponding to the type element selected.
This type of serial printer is increasingly being used in electric typewriters, output devices of computers and so forth, because of its clean printing, its ability to be used with ordinary printing papers and so forth, thanks to the printing with type elements impacting the paper. Hitherto, various serial printers using so-called daisey type wheels or vertically and rotatively movable type cylinders carrying type elements to impact the record paper have been known.
In the known serial printers using a daisey type wheel, however, the size of the carriage carrying the type wheel is inevitably increased because the carriage is typically required to carry also a motor for driving the type wheel, a hammer, and an electromagnetic device for actuating the hammer. The increased size of the carriage in turn necessitates an increased capacity of the motor for driving the carriage. In addition, various operations such as selection of the type element, shifting of the carriage, actuation of the hammer and the feeding of paper require independent driving sources such as motors or electromagnetic devices. In consequence, the size and weight of the printer as a whole are increased undesirably. Such printers, therefore, are not readily suitable for use as portable serial printers, particularly since such printers typically have three expensive motors as the driving sources for carriage shifting and paper feed and the like which are particularly large-sized and expensive. It is thus difficult to reduce production costs of such printers.
The second type of known serial printer using the vertically and rotatively movable type cylinder suffers the same disadvantages. Namely, independent and different driving power sources are required for various operations such as vertical driving of the type cylinder, rotation of the same, shifting of the carriage, impacting of the type wheel as a whole against the platen, and feeding of the paper, resulting in an en increased size and elevated production cost of the printer. The weight is increased also so that this type of serial printer cannot suitably be used in portable electric typewriters.